Various continuous data protection (CDP) methods and systems were developed in order to store and restore the content of persistent storage units. U.S. patent application publication serial No. 2005/0066118 of Perry et al., and U.S. patent application publication serial No. 2005/0193272, all being incorporated herein by reference, describe prior art devices and method for continuous data protection.
Virtual machines isolate an operating system from the computer platform that is used to execute the operating system. Operating systems running inside virtual machines can be executed by different computer platforms.
A single computer platform can support multiple virtual machines concurrently. Such a computer platform is commonly referred to as a logically partitioned platform. Each operating system or instance of an operating system is assigned a non-overlapping subset of the computer platform.
Typically, the multiple virtual machines are controlled by a hypervisor. The hypervisor can manage and enforce partition protection boundaries. See, for example, U.S. Pat. No. 6,839,892 of Dawking et al., which is incorporated herein by reference.
The state of a virtual machine can be stored (and restored) by using virtual machine check-pointing. The state of a virtual machine can be at least partially temporarily stored within various volatile memory units such as internal registers of the computer platform.
Due to the time gaps between CDP storage operations and between virtual machine snapshot operations the overall state of the computer platform at certain times is either unknown or requires relatively excessive restore operations.
There is a growing need to provide devices, computer program products and methods that will enable efficient restoration of information.